This piece originally appeared in U.S. News & World Report and was authored by Stephen Peters, HRC National Press Secretary.

It was with a familiar sickness of heart that I watched as President Donald Trump launched an all-out assault on the LGBTQ community and active duty service members by tweeting that he is reinstating a transgender military service ban.

You see, I've been there. My own service in the Marine Corps was cut short because of "don't ask, don't tell" – the archaic and deeply discriminatory law that barred gay, lesbian and bisexual Americans from serving openly in the military. I was discharged because I am gay. I still mourn the loss of the career I had aimed for, serving the country I love.

Sadly, Trump's heinous and disgusting action – which could lead to the discharge of as many as 15,000 transgender Americans serving our country at this critical time – is "don't ask, don't tell" all over again. Trump's nakedly political aim to isolate, target and discriminate against transgender troops courageously serving our country has, in a few hundred Twitter characters, threatened to return us to a deeply shameful policy that weakens our military. Discharging thousands of highly trained and talented troops just because of their gender identity would be unconscionable.

I was just out of college when I decided to enlist, after the tragic events of Sept. 11. Though I was proud to honorably serve my country in the U.S. Marine Corps, after re-enlisting for another four years, I knew I could no longer go on pretending I wasn't gay.

I wanted to continue to serve, but the law said I was suddenly unfit for duty, simply because of who I am. A huge burden was lifted off of my family's shoulders when "don't ask, don't tell" was finally repealed under President Barack Obama, allowing my Marine husband to keep his distinguished career. He's now serving a year-long deployment in one of the world's most dangerous areas.

So you can imagine my outrage that Trump would seek to implement this kind of discriminatory, unpatriotic policy. Our transgender service members wear the same uniform, take the same oath and are heroes who put their lives on the line to protect our country and promote security around the globe.

All of our brave troops – including my husband, who is currently serving in harm's way – are counting on us to have their backs, no matter their gender identity or sexual orientation.

Instead, since the day he set foot in the White House, Trump and Vice President Mike Pence have appointed anti-LGBTQ extremists across the government and sought to roll back our rights at every turn. It's bad enough that Trump and Pence oppose marriage equality, that they endorse license to discriminate laws, that they defend anti-LGBTQ measures like North Carolina's HB2, that they appoint anti-equality justices and that they campaign with anti-LGBTQ hate groups.

It is a new low to target thousands upon thousands of actively serving transgender members of the U.S. military, and impugn the honor of tens of thousands more who have served with valor and distinction — including more than 134,000 transgender veterans who are alive today. This attack undermines military readiness and harms the military's ability to recruit and retain the best and the brightest, regardless of their gender identity.

I hope that every service member and veteran who has fought for our country will see the injustice in what Trump and Pence have done. I hope they will join me in standing up to this disgraceful assault on our fellow service members.

We enlist and commission to protect our most fundamental values: freedom, justice, equality under the law. It is an outrageous tragedy that our commander in chief has decreed transgender troops – who are fighting for those ideals we all share – should be treated so shamefully.